We report polarization propagator calculations within the random-phase approximation of several isotropic moments and their directional components of the dipole-oscillator-strength distribution of H[sub 2] and of H[sub 2]O. The calculations show that there is strong dependence on the polarization direction of the incoming beam. The dependence of the moments on the molecular geometry is also discussed. In particular, the mean excitation energy for stopping is found to be very directionally sensitive, leading to the necessity of using directionally specific mean excitation energies when discussing oriented targets. It is possible that the sample phase dependence of the stopping power of watermore » may be in part due to directional effects in [ital I][sub 0]. A transferable bond mean excitation energy for the O-H bond is calculated, and is found to be constant within [plus minus]1% for ( )H-O-H from 95[degree] to 120[degree] at constant bond length [ital R][sub OH]. It agrees well with previous results.« less

Fission fragments from a /sup 252/Cf source and 72-MeV /sup 127/I ions from an EN-tandem accelerator have been used to sputter secondary ions electronically from samples of biomolecules like bovine insulin (5733 u). It is found that intact molecular ions of insulin are ejected from the surface at an angle which correlates with the incident ion direction. This study shows that from the ionized cylindrical region produced by the passage of a fast ion there is a direct radial momentum transfer, i.e., a nondiffusive process, which ejects large molecular ions.